diagnosis of dti - npuap€¦ · diagnosis of dti ‐ engineering view ‐ makoto takahashi, d....
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DiagnosisofDTI‐EngineeringView‐
MakotoTAKAHASHI,D.Eng.
HokkaidoUniversity,Japan
2002‐2007‐2012/2013
PresentaHonaboutShearForceatEPUAPin2002
2002‐2007‐2012/2013
Dr.JoyceBlack
(NPUAPPresident)
VeryimportantconferenceTurningpoint
Many UnKnowns about Shear Force
Dr. Laura EdsbergNPUAP at San Antonio in 2007
2002‐2007‐2012/2013UnKnowns! UnKnowns! UnKnowns!
2002‐2007‐2013
‘Tenyears’past…..!
Couldweextendourknowledge?What’snewtoday?
Today’sTopics
• FORCEontheskinsurface
• FEMmodelattheHIPandHEEL
• Bloodflowattheforearmunderpressureandshearforce
• UltrasonographyforDTI
Today’sTopics
• FORCEontheskinsurface
• FEMmodelattheHIPandHEEL
• Bloodflowattheforearmunderpressureandshearforce
• UltrasoundgraphyforDTI
NPUAPSTAGE(2007)
STAGEISTAGEIISTAGEIIISTAGEIV
SuspectedDeepTissueInjury Unstageable/Unclassified
h]p://minds.jcqhc.or.jp/n/medical_user_main.php
SuspectedDeepTissueInjury–depthunknown
• Purpleormaroonlocalizedareaofdiscoloredintactskinorblood‐filledblisterduetodamageofunderlyingsodHssuefrompressureand/orshear.TheareamaybeprecededbyHssuethatispainful,firm,mushy,boggy,warmerorcoolerascomparedtoadjacentHssue.DeepHssueinjurymaybedifficulttodetectinindividualswithdarkskintones.EvoluHonmayincludeathinblisteroveradarkwoundbed.Thewoundmayfurtherevolveandbecomecoveredbythineschar.EvoluHonmayberapidexposingaddiHonallayersofHssueevenwithopHmaltreatment.h]p://www.npuap.org/resources/educaHonal‐and‐clinical‐resources/npuap‐pressure‐ulcer‐stagescategories/
Causes of Tissue DamageInternal Factors:
Tissue / Cell Integrity
Anatomical Structure
etc
External / Interface Factors:
External Force
Skin Contact Conditions
Temperature and Humidity
Toxicity etc
etc
External Force
One of the Most Risk Factors
which causes Tissue Damage
z
x
yShear Force
Shear Force
Pressure
P
Z torque
Y torque
X torque
Force on Skin Surface
Three linear forces
Pressure, Shear
Three rotational forces
Six Degrees of Freedom
1st Shear Force Initiative
was started at 8th EPUAP,2005 in Aberdeen
Analysis of External Force Evaluation and Measurement
TwoDsofFinMarkeHng(Predia,molten)
One axis type strain gauge detects a shear force at skinsurface which is parallel to the skin
A self-inflatable air balloon measures a pressure whichis normal force at skin
96mm
70mm
Face:Shear force sensor
Back:Surface pressure sensor
Where
Skin Surface and Shallow Tissue
Middle Tissue
Deep Tissue
Where and How Shear Force works in Tissue
How
Shear Force at Skin Surface
Normal Force at Skin Surface
Today’sTopics
• FORCEontheskinsurface
• FEMmodelattheHIPandHEEL
• Bloodflowattheforearmunderpressureandshearforce
• UltrasoundgraphyforDTI
NormalForceatSkinSurfacechangestoShearForceatDeepTissuewithBonyProminence
Normal+ShearForceatSkinSurfacechangestoBigShearForceatDeepTissuewithBonyProminence
FiniteElementMethod(ModifiedModelfromChow(1978))
3D 3layerbuttock model
Bone
Muscle Fat
Skin
Future works
Today’sTopics
• FORCEontheskinsurface
• FEMmodelattheHIPandHEEL
• Bloodflowattheforearmunderpressureandshearforce
• UltrasoundgraphyforDTI
Blooddynamicsoftheskinandtheradialartery
Motorand
Gear Box
A/D000
PC BaseInstrument
PC
D/A
Pressure
Ultra soundinstrument
US probe
Indenter
Laser prove
Laser DopplerBlood Flowmeter
Radial artery
Shearforce
Pressure
Ball Screw
Load CellShear force
Blood Flow
Blood Velocity
Blood Volume
Pressure+ShearForece
Pressure75 mmHg
ShearForce
!
!"#
!"$
!"%
!"&
'
'"#
! !"#( !"( !")( '
Shear Force [N/cm²]
Nor
mal
ized
Blo
od F
low
SkinCapillary
RadialArtery
100 mmHg
50 mmHg
75 mmHg
ANCOVA **p < 0.01
*p < 0.05
**
*
Blood flow with Pressure and ShearForce
Blood flow of the radial artery more decrease
Today’sTopics
• FORCEontheskinsurface
• FEMmodelattheHIPandHEEL
• Bloodflowattheforearmunderpressureandshearforce
• UltrasoundgraphyforDTI
UltrasonographyforDTIResearch• Bedsidemeasurement
• LowcostfordataacquisiHon
Boneshape,SodHssuethickness,Skinshape
• ShortHmeforacquisiHon–abouttenminutes
• Bodyshapedatabydigitalcamera
• ElasHcitymeasurementbydurometer
UltrasonographyforDTIResearch• Subjectswerefourelderlies
• SixultrasonogramweretakenatlateralposiHon
median:redline horizontal:greenline
• Ittookintenminutes
Bonemodel Measurementskinregion
UltrasonogramofMediancrosssecHon
Z
X
Y
Subject2(T.O)83yrsH138cmBW30.9kg
UltrasonogramofHorizontalcrosssecHon
X
Y
26
Z
Subject2(T.O)83yrsH138cmBW30.9kg
MediancrosssecHon
Sacralcrest
Base27
HorizontalcrosssecHon
28
Sacralcrest
Base
CurvefipngfromBoneImaging
MediansecHon(0.5mminterval)
29
Sacralcrest
Base
HorizontalsecHon(0.5mminterval)
MediansecHon(0.5mminterval) HorizontalsecHon(0.5mminterval)
ExtrapolaHonoftheSacralcrest
30
TissuelayerThicknessofSubjects
ThicknessoftheSkin
ThicknessoftheSodHssuelayersismeasuredbyUSimaging
(a)thicknessofHssue
ThicknessoftheFatlayer
Sacralcrest
(b)differenceinthickness
skinfat
Total
Simplified3DSacralmodel
• ThemodelwasconstructedbySimulaHonsodware(ANSYS)ofFiniteElementMethod(FEM)
• VolumerenderingaderextrapolaHonusingthesplinecurvesforthesacrum,thefatlayerandtheskin
(b)Thesacrum,FatandSkin(a)thesacralcrestandthebase
Sacrum
Fat
Skin
FEMmodelanditsmaterialproperHes
• Elementtypeistetrahedronandtennodes• Numbersofelementsarearound100,000• BoneandSkinarelinearelasHc(Table1)• FatlayerissuperelasHcofOgden‐Foam
model(Table2)
Table1.BoneandSkinlayer
Ogden’sEquaHon
Table2.Ogden‐Foamparameters
SimplifiedSacralregionmodelWuetal.,2002
Yang’smodulus(MPa)
Poisson’sraCo
Bone 20000 0.3
Skinlayer
0.85 0.49
μ1(kPa) α1 μ2(kPa) α2 μ3(kPa) α3 β
‐181.15 5.511 30.69 6.571 153.64 5.262 2
• Solidplateispushed3mmdown
• HighvaluesofequivalentstressarefoundatboundariesofHssues
• Lowstressaccordingtomorethickness
Results
MediansecHon(sbjST) thicknessvs.stress
[MPa]
SuspectedDeepTissueInjury
sDTImodelandUSImaging
DTIisdefinedasafuncHon